Numbering and imprinting for printing serial codes on securities, banknotes, and the like has been done by additionally printing such codes on printed products which have already been subjected to printing such as offset printing or intaglio printing. Moreover, numbering cylinders of numbering and imprinting machines capable of such numbering and imprinting include numbering units having carved letters of predetermined digits. These numbering units are configured to be fed with an ink stored in an ink fountain through a number of rollers.
Patent Literature 1, for example, discloses an inking device of a numbering and imprinting machine as described above which is capable of feeding an ink to numbering units of a numbering cylinder.